Microstructural brain changes and their impact on hemorrhagic stroke recovery: a neurite orientation dispersion and density imaging-based study.

Background: Intracerebral hemorrhage (ICH) induces profound microstructural damage, particularly to axonal integrity and connectivity. This disruption severely compromises the efficiency and precision of neural signal transmission, serving as a key determinant of post-ICH functional outcome. Precise evaluation of these changes is therefore essential for prognostication and guiding targeted rehabilitation strategies. This study aimed to investigate the correlation between the patterns of microstructural changes in brain tissue following ICH and the patients' functional outcome and cognitive status based on neurite orientation dispersion and density imaging (NODDI). Methods: Thirty-six patients underwent 3-T magnetic resonance imaging (MRI) within 3 days of symptom onset. Functional outcome and cognitive status were evaluated via the modified Rankin scale (mRS) score and the Mini-Mental State Examination (MMSE) 90 days after onset. Individuals with an mRS score exceeding 2 were categorized into the poor function prognosis group. The intracellular volume fraction (ICVF), orientation dispersion index (ODI), and isotropic volume fraction (ISOVF) within the cortical gray matter, deep gray matter, and white matter of both the unaffected and affected hemispheres were assessed. To identify independent predictors of poor prognosis, multivariate logistic regression analysis was conducted. Additionally, Spearman correlation analysis was used to investigate the associations between NODDI indices and MMSE score. Results: The ODI of the white matter in the affected hemisphere was found to be an independent predictor of poor functional outcome of ICH [odds ratio 1.126; 95% confidence interval (CI): 1.004-1.263; P=0.042]. The area under the curve (AUC) value for predicting poor prognosis with ODI values in the affected cerebral hemisphere in conjunction with clinical variables was 0.910. Spearman correlation analysis indicated a significant negative correlation between the ODI of the deep gray matter on the affected side and MMSE score (R =-0.489; P=0.003). Conclusions: MRI metrics derived from the multishell diffusion model suggest that the early stage of ICH may result in the disruption of microstructural integrity. Damage to white-matter neurons in the affected cerebral hemisphere is correlated with functional impairment, whereas damage to deep gray-matter neurons in the same hemisphere is associated with a decline in cognitive outcome.